There are many available accumulation devices for conveyors. In cascading accumulators, the express or main conveyor system feeds into a broadened area with sides and a funnel shaped exit. When the exit is blocked, because for example the next machine or conveyor downstream is inoperable or jammed, product slides back up along the funnel shape and sides to fill the broadened area. Such accumulators are not well suited to handling delicate or unstable goods. During backups, product can be scuffed on its bottom and sides and unstable product can be easily knocked over. In side accumulators, a second conveyor belt operating perpendicular to the main belt conveys away product that is backing up. In addition to the dangers of scuffing and spilling previously referred to, there is here also the danger that small articles can be dropped or caught between the two conveyors. Vertical conveyors lift one or a row of backlogged product off and above the overloaded main conveyor. But again, scuffing and damage are a problem and this method is not suitable for small articles the size of pill bottles and tape cassettes disposed on end. Spiral accumulators create a buffer zone by conveying the product into a spiral path or a helical path upward then across to a helical path downward. Here, as in all of these devices, there is additional motion required which risks damage to the goods, especially small, delicate, or unstable products, and wastes energy.